6 When they heard the sound, they came on the run. Then when they heard, one after another, their own mother tongues being spoken, they were thunderstruck. 7 They couldn't for the life of them figure out what was going on, and kept saying, "Aren't these all Galileans? 8 How come we're hearing them talk in our various mother tongues?
Matthew Henry's Commentary on Acts 2:6-8
Commentary on Acts 2:5-13
(Read Acts 2:5-13)
The difference in languages which arose at Babel, has much hindered the spread of knowledge and religion. The instruments whom the Lord first employed in spreading the Christian religion, could have made no progress without this gift, which proved that their authority was from God.